A man was infected with the Usutu virus in New Aquitaine. This is the second case in France. What does the disease transmitted by this virus look like and should you be concerned about?
On November 10, 2022, the Regional Health Agency (ARS) of Nouvelle-Aquitaine confirmed in a press release a case of arbovirosis in a patient. This patient had not left the area in the weeks preceding the symptoms. It is therefore an indigenous case. For the record, a case is said to be indigenous if the person contracts the disease in their usual place of residence, without having previously traveled to an area where the virus is circulating. After a suspicion of infection by the dengue virus transmitted by the tiger mosquito, then a suspicion of infection by the West-Nile transmitted by the Culex mosquito, it was confirmed that this patient had indeed been infected with the Usutu virus. .
The Usutu virus, or Usuv, is a member of the genus Flavivirus and family Flaviviridae. It is an emerging virus of African origin. Its name comes from the place where it was first identified, in South Africa, in Swaziland, along the Usutu River in 1959. Cases in birds were later reported in Italy, Hungary, Switzerland, Spain and Germany. Human cases were described in Italy in 2009. The patients concerned were immunocompromised. In France, only one human case had so far been detected, it was in 2016 in Hérault (Occitanie region).
Symptoms of the disease and vector of contamination
Most of the time, Usutu virus infection is asymptomatic or minimally symptomatic. It is quite possible that cases have gone unnoticed. In the presence of symptoms, they may resemble those of the flu (asthenia, headaches). In immunocompromised people, the disease can take a serious form with neurological disorders: encephalitis or meningoencephalitis. Encephalitis is an inflammation of the brain.
The Usutu virus circulates among birds: blackbirds, sparrows, chickadees, robins, owls, owls, migratory birds… When a mosquito bites an infected bird, it becomes a carrier of the virus. We are talking here about ornithophilous mosquitoes of the genus Culex or common mosquito, and not tiger mosquitoes. Humans can be infected by the bite of a carrier mosquito. On the other hand, men cannot contaminate each other or infect mosquitoes.
Prevention involves protection against mosquitoes. Mosquito control operations were carried out in New Aquitaine at the places where the person infected with the virus had gone. This involves the removal of breeding sites and the night spraying of adulticide. Nevertheless, common mosquitoes are particularly abundant when temperatures are high. The drop in temperatures observed at the moment should naturally slow the circulation of the virus.